1. Field of the Invention
The present invention relates to a method of and an apparatus for feeding a piece of fabric to a sewing machine, and more particularly to a technique of feeding a piece of fabric previously formed as a cylindrical shape by sewing two opposite edges of the fabric together to a sewing portion of a sewing machine so as to sew a hem portion of the fabric after making one edge portion of the cylindrically shaped piece of fabric into a twice-folded, three layered band.
2. Description of the Prior Art
To perform so-called lapped-edge stitching (see FIGS. 12A, 12B, and 12C) by using a hem stitching sewing machine producing chain stitches, a fabric-edge lapping tool such as a twice folding tool and a fabric edge detector have conventionally been provided on the operator's side of the sewing portion of a sewing machine in the fabric feeding direction. Such lapped-edge stitching is performed in a so-called overlock stitching manner in which one edge portion of a cylindrically shaped piece of fabric is twice folded along the edge as to form a twice-folded three-layered band, and overcasting stitches are applied to the fabric so as to penetrate the thickness of the upper layer and of the fold forming middle and lower layers and also to enwrap the outer free edge of the upper layer. The fabric edge-lapping tool is operated manually when inserting the edge of a piece of fabric in order to form a twice-folded, three layered band. The fabric edge detector detects the edge of the fabric and operates in order to move the fabric horizontally while the fabric is being fed so that the overcasting stitches will accurately penetrate the fabric at the right locations.
The fabric edge-lapping tool and the fabric edge detector do not represent obstacles in the case of a flat-shaped piece of fabric. However, this is not true in the case of a cylindrically-shaped piece of fabric, particularly when the diameter of the cylinder is small. For instance, in the case of the cuff edge of a sleeve of a child's shirt, even if the sleeve is inserted around the cylindrically shaped bed of a so-called free arm sewing machine, the tool and the detector provided on the operator's side of the free arm will represent obstacles. More specifically, it has been extremely difficult and practically impossible to feed the fabric and accurately perform overlock stitching while manually inserting the edge of the fabric into the fabric edge-lapping tool and making the edge twice-folded, three-layered.
In order to eliminate these drawbacks, the present applicant has previously made proposals as disclosed in Japanese Patent Laid-Open Nos. 108081/1985 (corresponding to U.S. Pat. No. 4,580,512) and 122888/1986. According to these proposals, left and right supports are provided, and after one edge portion of a cylindrically shaped piece of fabric inserted around the supports has been made twice-folded and three-layered, the entire fabric is fed forward to a sewing portion of a sewing machine by moving the cylindrically shaped piece of fabric along the left and right supports and also moving the right support ahead together with the cylindrical piece of fabric. However, since the left support is secured to the frame of the sewing machine, while the right side of the inner peripheral surface of the fabric moves easily, the left side thereof is subjected to friction and moves only with difficulty. Consequently, the movement of the cylindrical piece of fabric differs in amount between the left and right sides, involving the risk that the twice-folded, three-layered band may collapse. In addition, because the right support moved ahead, a complicated and hence time-consuming operation of a plurality of clamps, particularly that of those on the right side, is required to enable the formation of the twice-folded, three-layered band and also the receiving and releasing of the fabric between these clamps.